This paper proposes a novel quantization parameter (QP) derivation module that constructs several spatiotemporal characteristics into key-frame QP determination through an efficient pre-analysis progress. A series of simplified prediction modes and a histogram statistic are employed to model the reference quality that key-frames provide to subsequent frames. An adaptive delta-QP value is generated to address the conflict between the low compression efficiency of intra-only frames and the critical predictive basis of temporal-underlying frames. The experimental result shows that the proposed method reduces 41.91% of peak-to-valley bitrate difference while leading to a 0.02% BDBR performance change, indicates that high-quality key-frames may not be indispensable in nowadays video compression frameworks. The proposed method has shown that the pre-analysis based QP optimization for intra-only frames is promising for the enhancement of transmission bandwidth utilization, which may hopefully provide new inspiration for bit allocation and rate control designs.